Rheostat.



F. EMBERGER.

RHEOSTAT.

APPLlCATION FILED SEPT. 6. I91]- 1 ,27 3 ,754:. Patented July 23, 1918.

FERDINAND EMBERGER, or BOARDMAN, OREGON.

. RHEOSTAT.

Specification of Letters Patent.

Patented July 23,1918.

Application filed September 6, 1917. Serial No. 190,049.

To all whom it may concern:

Be it known that I, FERDINAND EMBERGER, a citizen of the United Statesresiding at Boardman, in the county of Morrow and State of Oregon, haveinvented new and useful Improvements in Rheostats, of which thefollowing is a specification.

The invention relates to improvements in electric switches and seeks toprovide, as its principal purpose, a switch of this character for use inconnection with incandescent electric lamps, whereby the luminosity ofsuch lamps may be varied.

As a further purpose, the invention is designed to comprise a switch inconjunction with a rheostat, and to inclose the whole within a suitablecasing which is adapted to be carried by the flexible wire which carriesthe lamp which the switch controls, it

being the object to place the switch abovethe lamp and to connect it incircuit therewith by tapping one of the two conductors which feed thelamp.

It is a further purpose of the invention to provide a switch of thischaracter which may present a neat appearance, which may be easily andcheaply made, and which will effectively perform its function.

Other and further objects will be made apparent as the detaileddescription of the device progresses. 4

- While illustrated in but one form, it is to be understood that theinvention is not to be restricted to this particular form. An actualreduction to practice may make manifest certain changes or alterations,and these the right is claimed to make, in so far as they may becompatible with the'spirit of the ap ended claim.

n the accompanying drawings Figure 1 is an elevation of the invention,

Fig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 is a section taken centrally through the device at right anglesto the section of Fig. 2, but the upper portions of the casing areomitted in this figure.

Fig. 4 is a perspectlve view of the switch key and its attendantcontacting arm.

Referring to the drawings, there is shown a cylindrical casing whichcomprises the sections 1 and 2 that are attached together by means ofscrews 3, the latter being tangentially disposed with reference to thecylindrical surface and passing through body holes in the section 2 andentering threaded holes in the section 1. The cylindrical cas ing isprovided at either end with ornamental projections 4 formed half on thesection 2 and half on the section 1.

At approximately the center of the cylindrical casing-provlsion is madefor the resistance device and for the operatin arm of the switch, asubstantially semi-circular recess 5 being formed in the casing andexisting partly in the section 1 and partly in the section 2 andentrance to this recess is had through cylindrical holes 6 which open ateither end of the casin and are centrally disposed with reference 1;ereto, so that they may pass through ornamental rojections 4 whichconstitute suitable bushings for the flexible electric conductors 7 thatenter and leave the casing.

At the center of the semi-circular recess 5, an angularly movable stem 8is mounted, this stem having one end entering a cylindrical depressionformed in the section 1 but having the body portion passing through acylindrical hole formed in the section 2 on the outside of which itterminates in a key or thumb piece 9. A contact member 10 is secured to'the section 1 in the recess 5 by means of a screw 11 and this contactmember has one end in surrounding relation to the stem 8 and the otherend provided with a binding post 12. Oppositely disposed from thecontact member 10 there. is a resistance device 13 which is providedwith a suitable binding post 11 which is conveniently held in the recess5 at the point where one of the holes 6 enters the latter. sistancedevice 13 is provided with a plurality of arcuate arms, no two of whichare of the same radius but all of which are formed to curves generatedwith stem 8 as a center. The center arm 15 of this resist ance device isthe longest of the arms. The two arms 16 immediately adjoining this armon either side are somewhat shorter than This re-.

the arm 15 but on the other hand some sulating material and may beeither fiber or hard wood. Those parts of the device which are ofnecessity insulated from each other require no other insulation than thematerial of the casing on which they are mounted. Spaced away: from theextremity of the arm 15, there is a dead contact 21 on which the switcharm 18 is designed to rest when the circuit is open and this arm isprecluded from angular movement further tnan this dead contact by'meansof a pin 22 against which the side edge of the switch arm contacts.

'When the two sections of the casing are attached together, as shown inthe drawings, the stem 8 is prevented from longitudinal movement byhaving one end of the hub 19 abut the inner face of the section 2 andthe bottom face of the switch arm 18 abut the top face of the contactmember 10. The stem 8 is permitted to turn, however, and to move theswitch arm 18 over the several. arms 15, 16 and 17 of the resistancedevice These arms 15, 16 and 17 are designed to be made of any suitablehigh resistance material and their varying lengths give themcorrespondingly varying resistance values.

Since the resistance of an electric conductor varies directly with itslength the resistances of the arms 15, 16 and 17 are proportional totheir lengths. Therefore the arm 15 has the greatest resistance, thearms 16 less resistance'than the arm 15 and the arms 1? less resistancethan the arms 16. This arrangement has the effect of reducing theresistance interposed in the circuit as the switch arm 18 moves from thearm 15 to the arms 16 and then to the arms 17.

The flexible electric conductor 7 previously referred to is of theduplex type carrying wires 23 and 24: which are connected to oppositesides of an electric supply source, and transmit the current therefromto an incandescent lamp or other electric apparatus with which thepresent device is used. The conducting wire 23 is severed and one of itsends is connected to the binding post 14 and the other end to thebinding post 12, thus placing the present device in circuit with theapparatus which it is presumed to control.

It will be observed that when the switch arm 18 rests on the deadcontact 21 the circult is opened at this point. When the switch arm 18passes on to the arm 15, the circuit is closed, but through this longarm 15 whose resistance is sufficient to dim an incandescent light, orto cut down the speed of a motor which the device may control. As theswitch arm 18 passes on to the arms 16, the resistance is lessened andthe conductivity increased as a result of the resistance units beingthrown in parallel, 'lherefore, the incandescent lamp which it ispresumed is in circuit will burn brighter than previously, TWhen theswitch arm 18 passes on to the arms 17 it will have contact with all ofthe arms, resulting in another reduction of the resistance andincreasing the luminosity of the lamp. Finally, when the switch arm 18is in alinement with a binding post 1%, the resistance becomespractically nil, and the lamp burns with full luminosity.

What is claimed is 1:

In a rheostat, a cylindrical casing made of insulating materialcomprising two sections detachably connected, the said casing having acentral interior recess and holes opening cess which holes and recessare formed partly in one section and partly in the other, a resistancedevice contained within the central recess of the casing and attached toone of the sections thereof, the said resistance device comprising aplurality of arcuate arms concentric with each other but of varyinglengths, a switch arm slidably movable over the arcuate arms, so that itmay contact with one or several of said'arms, a con tact member securedto one of the sections of the casing and within the central recessthereof. an angularly movable stem fixed transversely in the casing, andbinding posts attached to both the contact member and the resistancedevice, the switch arm being carried by the stem, the contact memberhaving one end in surrounding relation to the stem and one face infrictional contact with the switch arm.

In testimony whereof I afiix my signature.

FERDINAND EMBERGER.

from both ends into the retill

